Electrical connections are a challenging aspect of underwater electrical system design, electrical conductive contact being the most common method of implementing an electrical mateable connector. Electrically conductive contact connectors are commonly subject to corrosion and contamination, which can result in a resistive contact point and failure of the connector function. In under water applications water must be excluded from the conductive contacts to prevent short circuits due to the partially conductive nature of water. Wet mating connections are even more challenging since water must be expelled from the conductive contacts during mating and care must be taken to ensure the signal is not applied to the connector while the contacts are exposed to the water before the connection is made to avoid rapid electrolytic corrosion. Connectors that do not rely upon direct conductive contact avoid these issues.
Additionally, any multi-pin connector must be rotationally aligned to ensure registration of the intended cross connections. This requirement can be problematic, particularly in applications where the connection point is not readily accessible by an operator such as connection by an autonomous system deep in the ocean. Slip ring connectors have been designed to avoid this issue but typically employ conductive brush contacts which are subject to corrosion and contamination issues, suffer continuous mechanical wear in rotating applications and present the challenging requirement of an underwater sealed rotating mechanical joint to exclude water from the brush contacts. An electrically insulated data and power connection which mates independent of angular alignment would be beneficial in many underwater applications.
Slip rings may be located at the axis of rotation or with an open bore positioning the ring coupling mechanism set out a radial distance from the axis of rotation. This second class of slip ring is defined as “off axis”.